We have recently defined a new HLA locus (SB) which maps centromeric to the other new genes of the HLA complex. During this year studies have included the importance of the genetic region marked by this gene in three different human diseases: dermatitis herpetiformis, juvenile onset diabetes, and kidney transplantation rejection. Previous studies of patients with dermatitis herpetiformis have been extended particularly with respect to family analysis. The results indicate that the positive association of DH with DR3 and the negative association with SB2 are most consistent with the hypothesis that risk is conferred by at least one as yet unknown HLA gene which occurs generally on HLA haplotypes which encode DR3 but encodes SB alleles other than SB2. Collaborative studies have been undertaken to use SB as an informative marker to map more precisely the susceptibility gene for juvenile onset diabetes; initial studies suggest that there is no SB antigen characteristic of "diabetic" haplotypes. The prediction has been made that the SB locus will function as a barrier to allogeneic tissue transplantation. "HLA-identical" donor/recipient pairs in which kidney transplantation has failed are being collected to test this prediction.